The invention relates to a radiant unit in the form of a portal equipped with a plurality of infrared lamps for use as a drying and baking unit and in particular for use as a drying and baking tunnel in the automobile industry.
From pamphlet Q-E1/14OP (April 1974 edition) of Heraeus Quarzschmelze GmbH, modular medium-wave infrared lamps are known which can be assembled in modular fashion to form planar infrared radiant units. For use in larger structures, these heating elements can be suspended from frames. Such modular lamps are used for drying and heating in the manufacture of small parts, in laboratories, and in the forming of thermoplastics.
For drying and baking of surface coatings, particularly in the automobile industry, the use of installations with infrared lamps of the type referred to above, for example, has proved highly advantageous since such installations can be kept very short, and since the heat required by the process can be directed onto the object with high precision. The ovens used in the automobile industry are constructed in the form of a portal equipped with individual infrared lamps and having a relatively short overall length, that is, an overall length considerably shorter than the vehicle being conveyed through the portal. In such drying and baking operations, it is important that the volatilized solvents, or other vapors or suspended particles present in the space, not deposit on the object being treated. Thus the air in the heating chamber surrounding the portal is continuously exhausted and cleaned, and filtered air is introduced.